My invention relates to a compander circuit, and particularly to a compander circuit having a compressor and an expander that are relatively small and that do not require inductors.
Companders (contracted from COMpressor and exPANDER) are used in transmitting voice signals to improve the signal-to-noise ratio of such voice signals. The dynamic range of voice signals is compressed (by the compressor part of the compander) from 60 db to 30 db, so that the lower level voice signals are transmitted at a relatively higher power level. After being transmitted over a line system, the received lower level voice signals are considerably higher than the system noise levels. The received voice signals are then expanded (by the expander part of the compander) to restore the original 60 db dynamic range. Such companders have been utilized extensively, because of this improvement in the signal-to-noise ratio, particularly with respect to the low level voice signals. However, these advantages are offset to some extent by prior art companders which, as far as I am aware, required transformers and inductors. Such transformers and inductors are, of course, relatively large and expensive. Accordingly, a compander having no transformers or inductors would be very desirable. In addition, companders would be used more if they could be adapted to the relatively small electronic circuit techniques now being used.
Accordingly, a primary object of my invention is to provide a new and improved compressor and expander for a compander circuit.
A relatively specific object of my invention is to provide a new and improved compander circuit that requires no transformers and no inductors.
Another relatively specific object of my invention is to provide a new and improved compander circuit that is relatively small and compact, and hence can be used in the relatively small electronic circuits now frequently required.